1. Field of the Invention
The present invention relates to a motor rotor, and more particularly relates to a motor rotor that can be manufactured easily and can reduce the cost of production.
2. Description of Related Art
With reference to FIG. 6, a conventional motor rotor 50 has an outer casing 51, multiple silicon-steel sheets 52, multiple copper sheets 53, multiple copper bars 54 and two holding rings 55. The silicon-steel sheets 52 are stacked and mounted in the outer casing 51 and each silicon-steel sheet 52 has a center and multiple through holes formed through the corresponding silicon-steel sheet 52 at intervals around the center of the corresponding silicon-steel sheet 52. The copper sheets 53 are mounted in the through holes of the silicon-steel sheets 52, extend out of the silicon-steel sheets 52 and each copper sheet 53 has two free ends extending out of the silicon-steel sheets 52 and two side face.
With reference to FIGS. 7 and 8, each side face of each one of the copper sheets 53 has a curved inner end and an outer end. The distance between the center of the silicon-steel sheet 52 and the curved inner end of the copper sheet 53 is smaller than the distance between the center of the silicon-steel sheet 52 and the curved inner end of the copper sheet 53. The area of the side face is convergent from the outer end to the curved inner end of the side face of the copper sheet 53. Then, the distance (L2) between the outer ends of two adjacent copper sheets 53 is larger than the distance (L1) between the curved inner ends of the adjacent copper sheets 53. Therefore, the copper bars 54 are inserted into the copper sheets 53 from the outer ends to the curved inner ends of the side faces of the copper sheets 53. With reference to FIGS. 9 and 10, after the copper bars 54 are mounted with the copper sheets 53, heating and sintering the copper sheets 53 and copper bars 54, cutting the superfluous sections of the copper bars 54 that go beyond an inner diameter of the outer casing 51 and respectively mounting the holding rings 55 around the copper sheets 53 and the copper bars 54 at the free ends of the copper sheets 53. Then, the conventional motor rotor 50 can be manufactured as shown in FIG. 6.
The conventional motor rotor 50 can be manufactured by the above-mentioned method. However, when manufacturing the conventional motor rotor, the copper bars 54 are needed to insert into the copper sheets 53 from the outer ends to the curved inner ends of the side faces of the copper sheets 53 due to the distance (L2) between the outer ends of two adjacent copper sheets 53 is larger than the distance (L1) between the curved inner ends of the adjacent copper sheets 53. Furthermore, the superfluous sections of the copper bars 54 that go beyond an inner diameter of the outer casing 51 are needed to cut and the holding rings 55 are needed to mount around the copper sheets 53 and the copper bars 54 to prevent the copper bars 54 from separating from the copper sheets 53 by a centrifugal force when the conventional motor rotor 50 is rotated. Therefore, the feature and the structure relationship of the distance (L2) between the outer ends of two adjacent copper sheets 53 is larger than the distance (L1) between the curved inner ends of the adjacent copper sheets 53 of the conventional motor rotor 50 will increase the complication and the cost of production.
Therefore, the present invention provides a motor rotor to mitigate or obviate the aforementioned problems.